# a = {
#     "name": "小明",
#     "age": 18,
#     "city": "北京市"
# }
# None
# print(a.get("gender"))

# print(a["gender"])

# for i in a.keys():
#     print(a[i])

# print(a.items())

# for k,v in a.items():
#     print(k,v)

a = {
    "name": "小明",
    "age": 18,
    "city": "北京市"
}
# print("gender" in a)

# for i in a.values():
#     print(i)

print(len(a))